Children's acquisition of morality is crucial for the well-being of individuals and for the functioning of society. The present research focuses on the early acquisition of the moral prohibition against harming others. Moral norms differ in meaning and importance from other types of norms, such as prudential norms (pertaining to danger to the child) and pragmatic norms (pertaining to inconvenience for others). These unique features of moral norms are recognized by preschoolers and adults, yet have often been overlooked by researchers on early social development. Caregivers face particular challenges when trying to convey moral values to children in the second year of life. This is a time when children increasingly engage in aggressive acts and other transgressive activities, yet have very limited abilities to understand verbal prohibitions and explanations. The proposed research investigates the role of vocal emotional communication in early moral development. It tests the hypothesis that caregivers use unique vocal signals to convey moral norms to young children and that these vocal signals in turn serve as powerful regulators of children's behavior. The project combines two methodologies to meet its goals: First, a longitudinal, naturalistic study is proposed to study naturally occurring interactions between mothers and children following children's moral, prudential, and pragmatic transgressions over the course of the second year of life. Second, an experimental study is proposed in which mothers vocal responses to moral, prudential, and pragmatic transgressions are elicited using video clips of child transgressions. These maternal vocal recordings are subsequently played back to the child to assess whether these vocalizations have differential effects on the child's engagement in a prohibited behavior. In both studies, we predict that mothers will use a more stern tone of voice (stable, low pitch and highly differentiated emphasis) in response to moral transgressions than in response to prudential and pragmatic transgressions. Next, we predict that the use of such tones of voice will be associated with greater compliance to interventions on moral transgressions both longitudinally (in the home observation study) and immediately (in the experimental study). This project will serve as a basis for a larger follow-up project studying the effects of socio-economic and cultural backgrounds more systematically and following the children from infancy to preschool and school age. The proposed investigation can to contribute to the scientific understanding of how very young children acquire moral norms, both by itself and as a foundation for subsequent studies research. Moreover, the research can inform interventions on parenting behaviors intended to promote the early acquisition of moral values.